Around 30 firefighters and three helicopters are battling a scrub fire in Titoki, west of Whangarei.
The blaze covers approximately 15-20ha.
Another helicopter and ground crews are protecting a nearby structure that is endangered by the flames.
A Fire and Emergency Services spokesman said crews were making good progress but the fire is not yet contained.
"The wind has dropped off which is helping," he said.
A resident on Wright Rd said the fire was located in a reserve across the river from their property.
"A couple of hours ago we heard a couple of choppers going over and then we saw quite a lot of smoke," he said.
"We went up the driveway and stood on a water tank at the top. There were about four choppers doing their thing and a substantial blaze.
"Of course, it doesn't help that it is about 33 degrees at the moment. It is really hot and dry."
The resident said the area was mostly uninhabited but he phoned the fire brigade to get some advice.
"They said they were giving no immediate advice but asked if we could get out if we needed to."
Another resident on the corner of Wright Rd and McCardle Rd said she could see a massive cloud of smoke.
"There is a big, huge cloud of brown smoke. I have been in town today and could see it from the main road, Mangakahia Rd. It is massive. There is a helicopter working on it and I have seen two fire engines go up."
She said the area was very rural, with big farms and areas of native bush.
There are about 10 properties on Wright Rd.
"It looks to be at the back of someone's property," she said. "All I can see is trees with this big bloom of smoke coming up above them."
Motorists are being warned to expect hazardous driving conditions.